export {}

abstract class Animal {
  eat (food: string): void {
    console.log(`呼噜呼噜的吃：${food}`);
  }

  abstract run (distance: number): void
}

class Dog extends Animal {
  run (distance: number): void {
    console.log(`四脚爬行 ${distance}`);
  }
}

const d = new Dog();
d.eat('食物');
d.run(100);